The statements in this section merely provide background information related to the present disclosure. Accordingly, such statements are not intended to constitute an admission of prior art.
Modeling or approximating characteristics of a system can be useful in a method to control the system. A system that operates unpredictably in different operating ranges is considered non-linear, meaning that observations made regarding the operation of the system on one operating range may not be useful to predict operation of the system in another operating range.
Fuel injectors are utilized to inject fuel into a combustion chamber of an engine. Fuel injectors provide pressurized fuel from a fuel rail to the combustion chamber. A fuel injector is activated at a timing or timings of a combustion cycle and remain open based upon a controlled fuel pulse width (FPW) to provide intended or desired fuel injections to the combustion chamber.
Internal combustion engines utilize valve timing or phasing strategies to effect changes to engine operation and performance. Valve opening and closing timings influence the thermodynamic cycle and the combustion process, including fuel efficiency, emissions, and engine torque level.
A number of advanced combustion strategies are known. Homogeneous-charge compression ignition (HCCI) operates at lower engine loads and speeds. HCCI strategies are designed to improve the efficiency and emissions of the internal combustion engine, through a combination of reduced pumping work, an improved combustion process, and improved thermodynamics. Methods are known to extend ranges at which HCCI can be operated, including utilizing negative valve overlap, reforming fuel during negative valve overlap, and spark-assisted HCCI operation.